Field of the Invention
The present invention relates to a work vehicle and a control method therefor.
Background Information
Work vehicles are equipped with a relief valve for ensuring the discharge pressure from a hydraulic pump does not become excessive when a large load is applied to the work implement. The relief valve opens when the discharge pressure of the hydraulic pump increases and reaches a prescribed relief pressure. Relieving a portion of the hydraulic fluid discharged from the hydraulic pump thusly prevents excessive increases in the discharge pressure of the hydraulic pump.
However, the energy from the hydraulic fluid relieved via the relief valve is converted to heat, and therefore that energy is lost. Accordingly, from the view of preventing energy loss, the discharge flow rate from the hydraulic pump should be kept as small as possible during relief.
In this regard, the work vehicle disclosed in Japanese Unexamined Patent Application Publication No. 2009-074405 limits the engine rotation speed during relief, in accordance with the discharge pressure in the hydraulic pump. In other words, the work vehicle in Japanese Unexamined Patent Application Publication No. 2009-074405 reduces the engine rotation speed during relief to reduce the discharge flow rate from the hydraulic pump.